The present invention relates to a compensation device for compensating the operation of an anti-skid brake control system when the vehicle makes a turn.
The anti-skid brake control system of the slip modulus type calculates the slip modulus in accordance with the following equation: (slip modulus) = (vehicle velocity -- wheel velocity) / (vehicle velocity) The anti-skid control system is enabled to prevent the occurrence of the skid condition when the slip modulus is beyond a predetermind value, preferably 0.20 - 0.30, after the driver brakes the vehicle.
In the anti-skid brake control system of the slip modulus type, a pick up coil is provided adjacent to the wheel of the vehicle for sensing the velocity of the wheel with the use of frequency signals from the pick up coil. The sensed value of the wheel velocity is then used for determining the vehicle velocity. In the case where a plurality of pick up coils are provided adjacent to a plurality of wheels, in general two pick up coils are provided adjacent to the left rear and right rear wheels, the maximum sensed value from the pick up coils is determined approximately as the velocity of the vehicle and the minimum sensed value from the pick up coils is determined as the velocity of the wheel. It is clear that the wheel velocities of the left rear wheel and the right rear wheel differ each other when the vehicle makes a turn. The anti-skid brake control system may be enabled when the vehicle makes a sharp turn, since the above-mentioned difference of the wheel velocities increases and hence the slip modulus may exceed the predetermined value. In the case where a pick up coil is provided adjacent a wheel and the sensed value from the pick up coil is treated electrically to determine the vehicle velocity and the wheel velocity, the anti-skid brake control system may be enabled when the vehicle makes a turn. That is, if the pick up coil is provided adjacent to the wheel which travels inside of the turn, the wheel velocity is less than the determined vehicle velocity.
In the anti-skid control system of the deceleration type wherein a pick up coil is provided adjacent to a wheel, the system may be enabled when the vehicle makes a sharp turn, since the detected deceleration value may exceed the predetermined value when the wheel provided with the pick up coil travels inside of the turn.
It is very dangerous that the anti-skid brake control system is enabled when the vehicle makes a turn, since a brake system does not work well in a normal strength even though the driver brakes the vehicle.
Accordingly, an object of the present invention is to provide an anti-skid brake control system which is not enabled at an erroneous condition.
To this end, the present system includes a steering wheel sensor for sensing an angle of a steering wheel when the vehicle makes a turn. Output signals of the steering wheel sensor are applied to a compensation circuit for compensating output signals of a wheel sensor which detects the velocity of the wheel of a wheeled vehicle, thereby preventing the erroneous operation of the anti-skid brake control system.